Flow over an airfoil

AIM

To determine the Drag and Lift forces on NACA0017 for various angle of attack and compare them.

OBJECTIVE

1.Model and Simulte the flow over aerofoil i.e NACA0017

2. For the angle of attacks 0,2,4,6,8,10 compare the lift and drag forces

THEORY

An airfoil is the cross-sectional shape of a wing, blade or sail etc. The NACA airfoils are aerofoil shapes for aircraft wings developed by the NACA. The shape of the NACA airfoils is described using a series of digits following the word "NACA". The parameters in the numerical code can be entered into equations to precisely generate the cross-section of the airfoil and calculate its properties. The DATA i.e coordinates of the aerofoil are used to create the profile.

CONCEPT

Air that travels over the top surface of the airfoil has to travel faster and thus gains dynamic pressure. The subsequent loss of static pressure creates a pressure difference between the upper and lower surfaces that is called lift and opposes the weight of an aircraft. Simillarly, the thrust which opposes drag force
As the angle of attack is increased, more lift is created. Once the critical angle of attack is reached the airfoil will stall.

FLOW SETUP

1.Initially, creating the profile of NACA0017 and extruding it to the required dimensions.

2. Provide the input domain.

Fluid- Air

Velocity-500 m/s (in X-direction)

Flow type- External

3. Since, we analyze the 2D flow we set domain to 2D which is to be done in computational domain.

4. Provide maximum space for the flow to occur in order to resist reflection of contour

5. Create the basic mesh, we need to refine the mesh at the surface of aerofoil in order to get more appropriate results.

6 . Set the surface goalsfor calculating the lift and drag forces.

7 .Compare the forces for various values of angle of attack.

OBSERVATIONS

SG Force (x) 1- DRAG FORCE

SG Force (y) 1- LIFT FORCE

CASE 1 -For 0 degree angle of attack

CASE 2 - @ 2 degree angle of attack

CASE 3 @ 4 degree angle of attack

CASE 4 @ 6 degree angle of attack

PRESSURE AND VELOCITY VARIATION IMAGES DURING SIMULATION

LINK: https://drive.google.com/drive/folders/1EsrfGIodFwjk6uozsPjRndRiWAVvAS8a?usp=sharing

CONCLUSIONS

1. From the plots, we get to know that lift force is a varies directly with the angle of attack.

2. @ 0 degree angle of attack very small amount of lift is generated due to the shape of aerofoil i.e if the profile is symmetric the lift is very small.

2. When we increase the angle of attack, the values of lift force also increases. Moreover, the magnitude of the lift force is dependent on the nature of the profile of the airfoil.

3. Simillarly, the value of drag force is higher at 0 degree , so it is not an optimal angle. This increase in drag force ends at a certain angle of attack, and the lift force also starts decreasing. This point is called the stalling point which is reffered as the critical angle of attack.

4. Lift and Drag forces also varies when we change the velocity of flow over the aerofoil. Hence, the parameters affecting the lift and drag forces are angle of attack, velocity, surface area on both sides, density of flow medium etc.